Sound-reproducing device



A ril14,1931. HM L N' 1,800,868

SOUND REPRODUCING DEVICE Filed Jan. 21, 1928 avwembo'c 720mm) 67mm Patented Apr. 14, 1931 UNITED STATES PATENT oFF'IcE THOMAS H. MGCLAIN, OF CLIFFSIDE PARK, NEW'JERSEY, ASSIGNOR T0 ROY G. MAO- PHERSON, 0F FRAMINGHAM, MASSACHUSETTS SOUND-REPRODUCING DEVICE Application filed. January 21, 1928. Serial No. 248,376.

This invention relates to an improvement in sound reproducing devices and has for its object to produce an electroresponsive device which may be either electrodynainic or electromagnetic or of any other type which will be so designed that it will act to transform anymechanical vibration into a plurality of independent or divided sources of electrical energy.

Heretofore, particularly in phonograph reproducing systems of the electrical type, it has been the common practice to transform the mechanical vibrations received from the record into a single electrical channel, covering all the audio frequencies, regulating merely this single channel of frequencies as desired to secure the best tone quality, or at least the tone quality most generally found satisfactory by the majority of listeners. It has been foundin practice that this regulation of the entire band or channel of audio phasized to the detriment of sweeter or purer tones; in other instances, where regulation by filtration is attempted, desirable frequencies are cut oil and anunnatural tone results. Thus, there have heenfor some time past, efforts madeto regulate tonal quality by suppression of undesirable frequencies in the tonal register, but in all instances, such offorts have proved inadequate dueto the fact that they were usually made at the output of the amplifying device, or else at the output of the pick-up device, andin all instances, were made by operation uponthe entire band of audio frequencies constituting the entire scale of reproduction of the pick-up device employed. a

The object therefore, of this invention is to provide a sound reproducing device par ticularly adapted for reproductionof phonoa graph or like records which will, as was heretofore mentioned, transform the mechanical vibrations into a plurality of independent or divided sources of electrical energy, such sources constituting separate audio freof device.

ferent listeners.

With these objects and such other objects as may hereinafter appear,in View, I have devised the particular arrangement of parts hereinafter set forth, andmore particularly pointed out in theqclaims appended hereto.

Reference is to be had to the accompanying drawing, in which the figure shown is a diagral'umatic view illustrating the application of my device. I

In the arrangement shown, 1 indicates diagran'nnatically a conventional form of pickup device used for theelectrical reprodue tion of phonograph records. The same may be of the electrodynamieor of the electromagnetic type, and isprovided with the usual armature 2, which carries the stylus 3 in any of the conventional ways. The stylus 3 moves in the record At 4E is shown a coil which is shown surrounding the armature and at 5 is shown another coil which may if desired be superim posed or wound over-the coil 4. These coils are so designed and arranged that they operate at highest efliciency :under particular bands of frequency. For the purposes of illustration, we might assume that the coil 4 has its highest operating efficiency or frequencies extending from 0 to 2500 cycles and the coil 5 operates mosteiiiciently on a band exgrooves as is usual in this type nals from the audio transformer 8. Asound amplifier or loud speaker 18 is placed in cir-- cuit with the output of the audio transformer 8. l

The coil 5 has its ends 12 and 13 connected to the primary of an audio transformer 14 which may be similar to the audio transformer 8. The output leads 15 and 1G ofthe audio transformer i l are connected by a va riable resistance or potentiometer 17.

From the'foregoing, the operation of my improved sound reproducing device will be readily understood. 'A secondsound amplifier or loud speaker 19 is placed in circuit with the output of the other audio transformer 1%. Assuming that the coil t operates on the low frequencies extending from 0 to 2500 cycles. This band of frequencies can be controlled as to volume or otherwise through the resistancel'l orany other similar controlling means. The other c'oil 5operating on a band of frequenciesextending from 2000 to 10,000

J made without departing from the'scope of my invention. v H c 7 Additionally WhileIhave shown and described the utilization of two coils, it will be obvious that as many coils as may be' required dividing the band of frequencies up into separate channels may be utilized.

With respect to the particular type of coils employed, I state that these may be arranged in any suitable manner dictated by proper constructional methods. The coils may be superimposed or. they may be positioned in any other way. The coils in one type of unit may be placed on the armature or they may be placed and used as field coils in other types. I

It is also possible to place and use such coils as oscillator coils placed externally of the actual pick-up, particularly inthe'ca'se where the pick-up employed is of the con-" denser or carbon type or in connection with a microphone.

Having described my invention as being particularly applicable for the reproduction of mechanical impulses and the transformation of such impulses lnlIOfilQCtIlCLl energy such as is done in phonographic reproduction, I do not however, limit myself to this particular employment of my invention as the same may be used in other ways and for other purposes.

It is also possible to reverse the use of the construction described so that phonograph records may be produced from this construction rather than reproduced in sound. It will be seen from theeconstruction and method of operation described that a great range of control is afforded by my invention and the tonal quality and volume of various notesinthe register is easily regulatable.

Thus, when bass notes are desired, the chan:

nel covering the lower, band of frequencies is regulated so that these notes are pronounced. The same is true ofany of the other channels of frequencies since the same are divided and easily pointed out. U

Having described one embodiment of my inventionpit is obvious that the sameis not to be restricted thereto but is broad enough to cover all structures coming within the scope of the annexedclaims; j

Whatl claimisi d 1. An electroresponsive device comprisin regulatable as was heretofore an electro-magnetic phonograph pick-pp device, inductances associated therewith, saidinductance'sbeing separately eflicient on different bands of sound'frequency, said in-' ductanceshaving,separate'outputs, and separate controlling means for regulation of the I outputs of said coils.

2. An electrical reproducer for phonographs comprising'an electromagnetic pick up device having a plurality of electromagnetic pick-up coils, audio amplifiers associ-' ated with said coils, and loudspeakers connected to said amplifiers.

3. An electric reproducer for phonographscomprising an electromagnetic pick-up de vice having a plurality of electromagnetic pick-up coils,'reproducin means having .a

corresponding nu'mber'o energizing coils,

and an audio amplifier connecting eachpick up coil with each energizing coil. 1

,4; An electrical reproducer, for phonographs comprising an electromagneticpickup device having a plurality of electromagnetic'pick-up coils, reproducing means having a corresponding number of energizing coils, and audio amplifiers connecting the re-. spective pick-up and energizing coils and tuned to resonance at different frequencies in i the audio.range'.-

graphs comprisingan electromagneticpickup device' having a vibrating armature and a plurality of "electromagnetic 'pick-up'icoils,

. 5. An electrical reproducer for phono-l reproducing means having a corresponding number of energizing coils, and "an audio amplifierconnecting each pick-up coil with each energizing; coil. 1 I

- 6. An electric reproducer forphonographs comprising an electromagnetic pickup device having a plurality of electromagnetic pickup coils, audio amplifiers associated with said coils, and loudspeakers connected to said amplifiers.

7 An electrical reproducer for phonographs comprising a plurality of electromagnetic pick-up coils, a common armature for said coils, reproducing means having units including energizing elements equal in number to the pick-up coils, and audio amplifiers connecting the respective pick-up coils and 

